#在字符串中使用变量
first_name = "gnu"
last_name = "linux"
full_name = f"{first_name}/{last_name}"
print("0: "+full_name)
print("1: "+full_name.title()) # 英文首字符大写
print("2: "+full_name.upper()) # 英文字符全大写
print("3: "+full_name.lower()) # 英文字符全小写
print("4: "+f"{last_name.title()} belong to {first_name.upper()}/{last_name.title()} is not {full_name.title()} !")